Electrochemical analytical cartridge

Abstract

An electro-analytical cartridge adapted for use in analyzing fluids. The cartridge includes an electrochemical device that measures ionic activity using ion-specific electrodes. The cartridge further includes a plumbing system composed of the electrochemical device and various wells or chambers which are interconnected by passageways. After introduction into the cartridge, liquid samples are measured out and transported to the electrochemical device utilizing a sequential application of centrifugal force followed by pressurization of the system. Reference fluid is transported from a reference fluid well or reservoir to the electrochemical device for use in measuring ionic activity. The cartridge may be used to measure the ionic activity of a wide variety of ions in fluids including bodily fluids.

What is claimed is: 
     
       1. A method for analyzing one or more properties of a fluid, said method comprising the steps of: introducing a fluid into an analytical cartridge wherein said analytical cartridge has an inner end and an outer end;   centrifuging said analytical cartridge to provide flow of fluid to a first location within said analytical cartridge wherein said inner end is located centrifugally inward relative to said outer end during said centrifuging;   pressurizing said analytical cartridge to provide flow of fluid to a second location within said analytical cartridge wherein said second location is located more toward the inner end of said analytical cartridge than said first location; and   measuring a property of said fluid within said analytical cartridge at said second location.   
     
     
       2. The method according to claim 1 wherein an electrochemical property of said fluid is measured. 
     
     
       3. The method according to claim 1 wherein said analytical cartridge comprises a reference fluid well for housing reference fluid and wherein said method comprises the step of pressurizing said reference fluid well after said centrifuging step to provide transport of reference fluid to said second location. 
     
     
       4. The method according to claim 1 wherein said fluid is analyzed for the presence of ions selected from the group consisting of potassium ions, sodium ions, calcium ions, carbonate ions and chloride ions. 
     
     
       5. The method according to claim 1 wherein said step of pressurizing said cartridge to provide flow of fluid to said second location is accomplished by compressing a septum having a compression surface located on the surface of said analytical cartridge. 
     
     
       6. The method according to claim 3 wherein said step of pressurizing said reference fluid well is accomplished by compressing a septum which forms part of said reference fluid well and is at least partially exposed on the surface of said analytical cartridge. 
     
     
       7. The method according to claim 2 wherein said electrochemical property of said fluid is measured using a thick film ion specific electrode. 
     
     
       8. A method for analyzing the electrochemical properties of a fluid which comprises the steps of: a) introducing said fluid into an analytical cartridge wherein said cartridge comprises: a housing comprising a cartridge body which has a top surface, bottom surface and outer walls defining a housing perimeter, said body further comprising an inner end and outer end;   a deposition well located in said cartridge body for receiving fluid to be analyzed, said deposition well having an inlet and an outlet;   an electrochemical device for measuring the ionic activity of said fluid, said electrochemical device comprising a sample inlet for receiving said fluid and a reference inlet for receiving a reference fluid, said electrochemical device being located more towards said cartridge body inner end than the outlet from said deposition well;   a sample passageway which is connected between said deposition well outlet and the sample inlet of said electrochemical device;   a reference fluid well for housing reference fluid, said reference fluid well having an outlet;   a reference fluid passageway which is connected between said reference fluid well outlet and the reference inlet of said electrochemical device;   a sample pressurization device for pressurizing said deposition well to provide controlled movement of sample fluid through said sample passageway; and   a reference fluid pressurization device for pressurizing said reference fluid well to provide controlled movement of reference fluid through said reference fluid passageway;     b) centrifuging said analytical cartridge with said inner end and said outer end of said cartridge body oriented so that said sample fluid flows from said deposition well into said sample passageway;   c) pressurizing said test well to provide flow of sample fluid from said sample passageway into said electrochemical device;   d) pressurizing said reference fluid well to provide flow of reference fluid from said reference fluid well to said electrochemical device; and   e) analyzing the electrochemical properties of said sample fluid in said electrochemical device.